Acrylamide again: Gingerbread and hartshorn

One more surprising discovery about acrylamide that I neglected to include in my recent roundup. Among the foods with the highest known acrylamide levels is gingerbread as it's traditionally made in northern Europe--so high that in Holland, gingerbread consumption alone accounts for something like a sixth of the total year-round acrylamide intake. This is despite the fact that wheat flours don't contain nearly as much asparagine as potatoes.

Over the last couple of years, Thomas Amrein and colleagues at the Swiss Federal Institute of Technology in Zurich have shown that the culprit is the traditional leavening agent: not familiar baking soda or powders, but ammonium bicarbonate, which is sometimes called hartshorn because it was originally obtained by heating deer antlers. Ammonium carbonate is especially suited to thin, dry cookies, because when heated it releases ammonia and carbon dioxide gases, but no water. So the cookies cook and dry out faster, and the pungent ammonia gets completely baked out, rather than lingering in a thicker mass. (The European gingerbreads are made from dough sheeted to about 7 mm thick, or a shade over 1/4 inch, baked for 10 minutes at 360-380 degrees F, 180-190 degrees C.)

The problem with ammonium carbonate is the ammonia that it releases during baking. It reacts with glucose and fructose in the dough to form unusual molecules that in turn react very efficiently with asparagine to form acrylamide. The Swiss gingerbread dough is made with glucose, fructose, and honey; molasses also contains a lot of glucose and fructose. Ordinary table sugar, sucrose, is not vulnerable to attack by ammonia.

So it's easy to make low-acrylamide gingerbread: either use a standard sodium bicarbonate leavener, or use table sugar for the sweetener, or both.